1. Field of the Invention
This invention relates to a key input apparatus for inputting information into various electronic equipments, such as computer or a computer applied equipment.
2. Description of the Prior Art
A key input apparatus comprising a large number of key switches is used for inputting the information into an electronic equipment, such as a computer or a computer applied equipment.
The simplest construction of the key input apparatus is to connect terminals of the large number of key switches and input parts of the main body at the electronic equipment by use of independent signal conductors so as to transmit signals from the key switches separately to the input ports respectively. Such constitution, however, increases corresponding to the number of key switches and the number of signal conductors between a key board or a console panel on which the key switches are mounted and the main body having input ports, thereby creating a problem in that when the number of terminals and connectors increases, the rate of the occurrence of trouble, such as imperfect contact or disconnection is high, and simplification of the design and work for wiring package or maintenance, is remarkably impeded additionally, the use of electronic equipment directed to miniaturization or integration is impeded from being reduced for miniaturization. In order to solve the above problem, a key input apparatus disclosed in the Japanese Patent Publication No. Sho 53-20331 (1978) has been proposed, which is provided with two signal conductor groups in a matrix and a key switch to each node so that the signal conductors between the key board as above-mentioned and the main body fairly decrease in number, but this reference has a defect in that eleven signal conductors are still required for, for example, thirty key switches and a control circuit for discriminating each switch is complex.
The conventional key input apparatus has fixed arrangement of keys on the keyboard, which arrangement cannot be desirably changed by a user. For example, FIG. 1 shows a ten key 61 for a telephone, in which numeral keys of 1 through 9 are disposed from the leftside upper portion to the rightside lower portion. On the other hand, FIG. 2 shows a ten-key 62 for a desk-top calculator, in which the numeral keys of 1 through 9 are disposed from the leftside lower portion to the rightside upper portion. It depends on the purpose for use or experience in use or choice of the user which key arrangement is convenient to use, but conventionally, the change of arrangement corresponding to the choice of user has been impossible. In a case where the key arrangement is intended to be changed due to an improvement in the apparatus or modification in specification, the change in arrangement also is not easy for a maker as well as the user.